It is known that a fluorescent substance is mixed in a cosmetic (for example, patent document 1). Such cosmetic is expected that the color of skin is adjusted by color development derived from the fluorescent substance and an unconventional cosmetic property is expressed by specific color derived from the fluorescence. Especially, a compound having a red fluorescence is expected to produce an effect of making the facial color appear bright by providing reddish tint to the skin.
However, an organic fluorescent substance such as 3-hydroxypyrene-5,8,10-trisulfonic acid which has been proposed, and an inorganic fluorescent substance such as NaCl:Mn have not been used substantially because they are composed of elements and molecules causing the risk of adverse influence for the human body and their safety is not confirmed. On the other hand, mineral-based fluorescent substances such as axinite (aluminum calcium borosilicate), calcite (calcium carbonate), and petalite (aluminum lithium silicate) that are considered relatively safe have been proposed (see patent document 2) but they may not be used in a cosmetic because of an insufficient color development.
A compound represented by Mg2TiO4:Mn4+ has been known (for example, patent document 3 and nonpatent document 1. However, the compound of patent document 3 has been investigated as a fluorescent substance for LED and has not been known as a cosmetic component.
Patent document 4 discloses that a composite metal compound is used as an ultraviolet absorbing agent. However, patent document 4 discloses only general description about very wide compounds, and never discloses specific description about compounds having fluorescence.